/*
* Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.max.vm.heap;
import com.sun.max.unsafe.*;
import com.sun.max.vm.actor.holder.*;
import com.sun.max.vm.layout.*;
import com.sun.max.vm.reference.*;
/**
* Encapsulates the basic logic for walking over cells in a heap region, and
* invokes {@link CallbackCellVisitor#callback} for each object found.
*/
public abstract class CallbackCellVisitor implements CellVisitor {
@Override
public Pointer visitCell(Pointer cell) {
final Pointer origin = Layout.cellToOrigin(cell);
final Hub hub = UnsafeCast.asHub(Layout.readHubReference(origin).toJava());
Object object = Reference.fromOrigin(origin).toJava();
if (!callback(object)) {
return Pointer.zero();
}
if (hub.specificLayout == Layout.tupleLayout()) {
return cell.plus(hub.tupleSize);
} else {
return cell.plus(Layout.size(origin));
}
}
/**
* Callback on a visited object.
* @param object
* @return {@code true} to continue then walk, {@code false} to abort.
*/
protected abstract boolean callback(Object object);
}